When to use .txt in Markdown

Markdown extensiions

Lately there was some discussion referring to Markdown extensions. The use of .md was in favor of normalization Markdown extensions, instead of using .mdown, .markdown, .text, .txt or otherwise.
I agree with that, with one exception. If you are working with multiple Markdowns files at the same time and there is no internet connection, it is handy to use .txt instead of .md. I'll explain why:

I write all my files in Editorial, an awesome app for automating a lot of workflows with Markdown. Editorial is in sync with Dropbox
(Dropbox/Apps/Editorial/), a two-way synchronization. Very convenient.
I use Documents from Readdle as my file management system and Documents can also enable two-way sync with Dropbox (Dropbox/Apps/Editorial/).
If you use .txt as a Markdown extension, you can edit the files in Documents, even if there is no internet connection. You don't have to download your file manually to your iPad. With .txt Documents do that automatically for you.

After the internet connection has been restored, Documents will sync with Dropbox and Dropbox will sync with Editorial. Very handy indeed.